 #!/usr/bin/env python3
"""
主程序入口文件
"""
def main():
    print("Hello, World!")
print("Welcome to my project!")
if __name__ == "__main__":
    main()
def calculate_sum(a, b):
    
    return a + b

def calculate_diff(a, b):
    
    return a - b

def calculate_multiply(a, b):
    
    return a * b

def calculate_divide(a, b):
    
    if b != 0:
        
        return a / b
def calculate_divide(a, b):
    
    if b != 0:
        
        return a / b
    
    return None
